Compound steam engine — effect on temperature range and cylinder condensation: State whether it is correct that compounding reduces the temperature range per cylinder and thereby reduces condensation losses.

Introduction:
Condensation on cylinder walls in steam engines is influenced by the temperature swing experienced during admission and expansion. Compounding (expanding steam in successive cylinders) is a classic method to reduce these losses and improve efficiency.

Given Data / Assumptions:

• Multi-cylinder expansion (e.g., high-pressure then low-pressure cylinder).
• Similar overall expansion ratio compared with a single-cylinder case.

Concept / Approach:
By dividing the total expansion among multiple cylinders, each cylinder experiences a smaller temperature drop between admission and exhaust. Smaller temperature gradients reduce heat flow to and from the cylinder walls each cycle, lowering condensation during admission and re-evaporation during expansion.

Step-by-Step Solution:

Verification / Alternative check:
Indicator diagrams and thermal analyses show decreased wall heat transfer and improved mean effective pressure for compounded engines at similar conditions.

Why Other Options Are Wrong:

• “Incorrect”: contradicts standard rationale for compounding.
• Requiring zero clearance or superheat: compounding benefits occur even without these idealizations, though superheat can further help.
• Indeterminate: the trend is well-established in engine theory.

Common Pitfalls:
Assuming compounding primarily increases power; its key advantage is thermal efficiency via reduced condensation and better expansion control.

Final Answer: